Breast Tumors in Black Women Have More Abnormal DNA

Breast Tumors in Black Women Have More Abnormal DNA

WASHINGTONBlack women have long been known to suffer higher breast
cancer mortality and to experience worse 5-year survival rates than whites.
Even controlling for disease stage, they are more likely to fail treatment
and have worse outcomes, said Lisa A. Newman, MD, MPH. The question
therefore arises, she said, whether these differences reflect biological
variation or social inequality.

Speaking at the 8th Biennial Symposium on Minorities, the Medically
Underserved, and Cancer, Dr. Newman reported data "strongly"
implying that those differences do not derive solely from socioeconomic
disparities. Rather, she said, pathological and flow cytometry comparisons
of tumors in black and white women suggest that tumors in black women
proliferate and accumulate abnormal DNA more rapidly than tumors in white
women.

Dr. Newman described a study comparing the proliferative indices of
breast tumors from 347 blacks and 184 whites. The women constituted a
consecutive series of patients undergoing surgery over a 5-year period in
the same comprehensive cancer center, one "ideally suited" for
this comparison because it serves a large black population, she said.

Although the mean ages of the two groups were comparable, 57.6 years for
black women and 57.8 for whites, nearly twice the percentage of black women
(11% vs 5% of the whites) were younger than 40. This "age distribution
is hard to explain on the basis of socioeconomic factors revealed by the
study," Dr. Newman said, adding that researchers have found a
"similar younger age distribution in native African breast cancer
patients."

The black women also had significantly larger tumors than the white
women, with a mean tumor size of 3.8 and 3.1 cm, respectively. In addition,
the tumors in black women were more advanced in stage and significantly more
likely to be negative for estrogen receptors (53% vs 47% for white women)
and progesterone receptors (59% vs 41% for white women).

The higher S-phase fraction of 11.4% in black women, compared with 9.6%
in white women, is also prognostically unfavorable, she said. The
lymph-node-negative and estrogen-receptor-negative patients showed the
largest ethnic differences in mean S-phase fraction.